Circuit interrupter with optical connection

Abstract

Circuit interrupter positioned between supply circuit and load circuit includes fault detection circuit that senses wave forms to the load circuit, fault processing circuit that detects presence of fault and generates fault output signal when fault detected, and control circuit switch connected to fault processing signal output, wherein control circuit switch is opened by presence of fault output signal, thus isolating load circuit from supply circuit. Preferably fault processing circuit and control circuit are optically linked, such that when fault is detected, control circuit switch is opened by optical fault output signal, thus isolating load circuit from the supply circuit. Circuit interrupter may couple another circuit interrupter via power distribution control unit, optionally manageable remotely via automated control interface.

The invention claimed is: 
     
       1. A circuit interrupter comprising:
 a solid-state switch serially connected between a line input terminal and a load output terminal of the circuit interrupter, and configured to be placed in one of (i) a switched-on state to provide an electrical connection in an electrical path between the line input terminal and the load output terminal, and (ii) a switched-off state; 
 switch control circuitry configured to control the solid-state switch, wherein the switch control circuitry comprises: 
 a driver circuit configured to generate a drive voltage using current drawn from an input power source applied to the line input terminal of the circuit interrupter, wherein the drive voltage is applied to a control input of the solid-state switch to place the solid-state switch in the switched-on state; 
 a fault detection circuit configured to (i) sense a voltage level across a sense resistor which is serially connected with the solid-state switch in the electrical path between the line input terminal and the load output terminal and (ii) generate a fault output signal in response to detecting a fault condition based on the sensed voltage level across the sense resistor; 
 a control switch connected to the fault detection circuit and configured to place the solid-state switch in the switched-off state, in response to the fault output signal generated by the fault detection circuit; and 
 an optical switch configured to place the solid-state switch in the switched-off state, in response to an optical control signal applied to the optical switch. 
 
     
     
       2. The circuit interrupter of  claim 1 , wherein said circuit interrupter is coupled to at least one other circuit interrupter via a power distribution control unit. 
     
     
       3. The circuit interrupter of  claim 2 , wherein the power distribution control unit is configured to be managed remotely via an automated control interface. 
     
     
       4. The circuit interrupter of  claim 1 , wherein the solid-state switch comprises a first MOSFET switch and a second MOSFET switch serially connected between the line input terminal and the load output terminal of the circuit interrupter, wherein the sense resistor is serially connected between the first and second MOSFET switches. 
     
     
       5. The circuit interrupter of  claim 1 , wherein the driver circuit comprises a voltage clamping circuit configured to generate the drive voltage to drive the solid-state switch. 
     
     
       6. The circuit interrupter of  claim 5 , wherein the clamping circuit comprises a capacitor and a Zener diode connected in parallel. 
     
     
       7. The circuit interrupter of  claim 1 , wherein the fault detection circuit comprises an operational amplifier having first and second input terminals connected across the sense resistor, and an output terminal connected to the control switch. 
     
     
       8. The circuit interrupter of  claim 7 , wherein the control switch comprises a bipolar junction transistor device having a base terminal connected to the output terminal of the operational amplifier. 
     
     
       9. The circuit interrupter of  claim 1 , wherein the optical switch comprises a phototransistor device. 
     
     
       10. The circuit interrupter of  claim 1 , further comprising an isolation circuit which is configured to shunt leakage current away from a load circuit connected to the circuit interrupter, when the solid-state switch is in the switched-off state. 
     
     
       11. A method, comprising:
 controlling a solid-state switch, which is serially connected between a line input terminal and a load output terminal of a circuit interrupter, to place the solid-state switch in one of (i) a switched-on state to provide an electrical connection in an electrical path between the line input terminal and the load output terminal of the circuit interrupter, and (ii) a switched-off state; 
 wherein controlling the solid-state switch comprises:
 generating a drive voltage using current drawn from an input power source applied to the line input terminal of the circuit interrupter; 
 applying the drive voltage to a control input of the solid-state switch to place the solid-state switch in the switched-on state; 
 sensing a voltage level across a sense resistor which is serially connected with the solid-state switch in the electrical path between the line input terminal and the load output terminal; 
 generating a fault output signal in response to detecting a fault condition based on the sensed voltage level across the sense resistor; and 
 placing the solid-state switch in the switched-off state, in response to generating the fault output signal; and 
 
 wherein controlling the solid switch further comprises:
 applying an optical control signal to activate an optical switch of the circuit interrupter; and 
 placing the solid-state switch in the switched-off state, in response to the activation of the optical switch. 
 
 
     
     
       12. The method of  claim 11 , wherein generating the drive voltage using current drawn from the input power source applied to the line input terminal of the circuit interrupter comprises charging a clamping circuit to generate the drive voltage to drive the solid-state switch. 
     
     
       13. The method of  claim 11 , wherein:
 sensing the voltage level across the sense resistor comprises applying the sensed voltage level across first and second input terminals of an operational amplifier; and 
 generating the fault output signal comprises the operational amplifier generating the fault output signal and outputting the fault output signal, in response to detecting a fault condition based on the sensed voltage level across the sense resistor. 
 
     
     
       14. The method of  claim 11 , wherein placing the solid-state switch in the switched-off state, in response to generating the fault output signal, comprises activating a control switch in response to the fault output signal, wherein activation of the control switch results in deactivation of the solid-state switch. 
     
     
       15. The method of  claim 11 , further comprising activating an isolation circuit to shunt leakage current away from a load circuit connected to the circuit interrupter, in response to solid-state switch being placed in the switched-off state. 
     
     
       16. A circuit interrupter, comprising:
 a first solid-state switch serially connected between a first line input terminal and a first load output terminal of the circuit interrupter, and configured to be placed in one of (i) a switched-on state to provide an electrical connection in a first electrical path between the first line input terminal and the first load output terminal, and (ii) a switched-off state; 
 a second solid-state switch serially connected between a second line input terminal and a second load output terminal of the circuit interrupter, and configured to be placed in one of (i) a switched-on state to provide an electrical connection in a second electrical path between the second line input terminal and the second load output terminal, and (ii) a switched-off state; 
 switch control circuitry configured to control the first and second solid-state switches, wherein the switch control circuitry comprises: 
 a first driver circuit configured to generate a first drive voltage using current drawn from an input power source applied to the first and second line input terminals of the circuit interrupter, wherein the first drive voltage is applied to a control input of the first solid-state switch to place the first solid-state switch in the switched-on state; 
 a second driver circuit configured to generate a second drive voltage using current drawn from the input power source applied to the first and second line input terminals of the circuit interrupter, wherein the second drive voltage is applied to a control input of the second solid-state switch to place the second solid-state switch in the switched-on state; 
 a fault detection circuit configured to (i) sense a voltage level across a sense resistor which is serially connected with the first solid-state switch in the first electrical path between the first line input terminal and the first load output terminal and (ii) generate a fault output signal in response to detecting a fault condition based on the sensed voltage level across the sense resistor; 
 a control switch connected to the fault detection circuit and configured to place the solid-state switch in the switched-off state, in response to the fault output signal generated by the fault detection circuit; and 
 an optical switch configured to place the first solid-state switch in the switched-off state, in response to an optical control signal applied to the optical switch. 
 
     
     
       17. The circuit interrupter of  claim 16 , wherein the fault detection circuit comprises an operational amplifier having first and second input terminals connected across the sense resistor, and an output terminal connected to the control switch. 
     
     
       18. The circuit interrupter of  claim 17 , wherein the control switch comprises a bipolar junction transistor device having a base terminal connected to the output terminal of the operational amplifier. 
     
     
       19. The circuit interrupter of  claim 16 , wherein the optical switch comprises a phototransistor device. 
     
     
       20. The circuit interrupter of  claim 16 , further comprising an isolation circuit which is configured to shunt leakage current away from a load circuit connected to the circuit interrupter, when at least the first solid-state switch is in the switched-off state.